1. Field
Embodiments of the invention relate to cellular networks and/or wireless communication systems, such as the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) and Long Term Evolution (LTE) Evolved UTRAN (E-UTRAN), Global System for Mobile Communications (GSM), Wideband Code Division Multiple Access (WCDMA), or any other wireless communications system.
2. Description of the Related Art
In wireless communications, a heterogeneous network (HetNet) is a network where different types of nodes are participating in the communication. More specifically, the HetNet scenarios in cellular communication systems are scenarios with different types of base stations (BSs). For example, besides the most common rooftop or mast located macro BSs, the HetNet scenario in the 3rd Generation Partnership Project (3GPP) takes into account the deployment of lower power BSs, such as small outdoor pico BSs, micro BSs, and even smaller home or femto BSs.
Compared to macro BSs, the pico, micro, and femto BSs have lower transmission power, for example 3GPP defines maximum transmission power for pico BS and femto BS to stay within ±2 dB from the rated output power of 24 dBm and 20 dBm, respectively. These values are per carrier and correspond to single antenna port—doubling the number of antenna ports reduces the limit by 3 dB. For a macro BS, the output power is limited by spectrum regulations. A typical output power value for a macro BS is 46 dBm. The main purpose behind deployment of pico, micro, and femto BSs is to bring higher data rates to user equipment (UEs) that are connected to them and to offload traffic from the macro BSs.